JPS6220917Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a magnetic tape winding device, and particularly to improvements in magnetic tape winding devices for video tape recorders and audio tape recorders.

Magnetic tape is used in video tape recorders and audio tape recorders to record video and audio. For example, a video tape recorder for recording video includes a tape reel for winding a magnetic tape and a magnetic head for recording on the magnetic tape. In order to correctly record or reproduce images, etc., it is necessary to send the magnetic tape to the magnetic head at a constant speed. However, when winding a magnetic tape, the winding amount of the tape reel changes between the beginning and the end of winding the magnetic tape, and the tension of the magnetic tape changes. As a result, the amount of conveyance of the magnetic tape per unit time changes, making it impossible to obtain a correct reproduction signal from the magnetic tape. For example, in the case of an audio tape recorder, a correct audio signal cannot be obtained, and in a video tape recorder, a correct horizontal and vertical synchronizing frequency cannot be obtained. Therefore, conventional magnetic tape winding devices have a tension control function to keep the tension of the magnetic tape constant.

FIG. 1 provides the background to this invention and is a diagram showing a part of a conventional magnetic tape winding device.

In the configuration, a motor 2 is provided at the bottom of the mounting plate 1 . A rotating shaft 3 of the motor 2 projects above the surface of the mounting plate 1. A take-up reel 5 for winding up the magnetic tape 4 is attached to the protruding shaft 3. As the motor 2 is driven, the take-up reel 5 is rotated counterclockwise (in the direction of arrow A).
A lever 6 is provided at a position facing the motor 2. The lever 6 is supported by a shaft 7 and is rotatably provided around the shaft 7. At one end of the lever 6,
A pole 61 is provided. This pole 61 is provided on the side where the magnetic tape 4 receives tension from the take-up reel 5 and a capstan (not shown).
A fixed end 8 is fixed to the mounting plate 1 on the side of the lever 6 facing the motor 2. This fixed end 8 and pole 61
A spring 9 is locked to the lever 6 near the.
A light emitting diode 10 and a light emitting diode 10 are mounted on the mounting plate 1 on the side facing the pole 61 of the lever 6.
A phototransistor 11 is provided opposite to. A light shielding piece 62 is formed on the side of the lever 6 facing the pole 61. The light shielding piece 62 is connected to the lever 6
The light-emitting diode 10 rotates as the light-emitting diode 10 rotates.
and the phototransistor 11. The elastic coefficient of the spring 9 and the positional relationship of the light-shielding piece 62 are selected so that the light-shielding piece 62 is in a position (toward the right in the figure) where it does not block light from the light-emitting diode 10 when there is no tension on the magnetic tape 4. . Further, when the tension of the magnetic tape 4 reaches a certain value, the light shielding piece 62 closes the light emitting diode 10.
The position that completely blocks the light from (towards the left in the diagram)
chosen to come.

FIG. 2 is a circuit diagram of a conventional magnetic tape winding device.

Below, with reference to FIGS. 1 and 2, the operation of the conventional magnetic tape winding device will be explained along with the specific circuit configuration shown in FIG.

When the motor 2 starts rotating, the magnetic tape 4 is taken up by the take-up reel 5. Then, the tension of the magnetic tape 4 is applied to the pole 61, and the lever 6 begins to rotate counterclockwise against the elastic force of the spring 9. At this time, the light shielding piece 62 moves to the left in the figure and gradually begins to shield the light from the light emitting diode 10. As a result, the amount of light received by the phototransistor 11 from the light emitting diode 10 gradually decreases compared to when there is no tension on the magnetic tape 4. The collector-emitter current of the phototransistor 11 decreases as the amount of light received decreases. Accordingly, the input voltage to the base of transistor 15 increases, and the collector-emitter current of transistor 15 decreases. By this,
The voltage at the base end of the transistor 18 decreases,
Reduce collector-emitter current. That is, the current supplied to the motor 2 decreases. This reduces the driving torque of the motor 2 and reduces the tension on the magnetic tape 4.

In this way, even if the amount of winding of the magnetic tape 4 increases, the tension of the magnetic tape 4 is controlled to be constant.

For example, in a VHS video tape recorder, the radius changes from 1.3 to 4.3 cm for a two-hour tape, and during this time the tension of the magnetic tape 4 is controlled to about 10 g.

When the magnetic tape 4 is fed, if the friction torque of the rotating part of the motor exceeds 13 g-cm, the tension of the magnetic tape 4 will exceed 10 g. in this case,
There was a problem in that the light shielding piece 62 completely shielded the light from the light emitting diode 10, making it impossible to control the tension of the magnetic tape 4.

Therefore, the main purpose of this invention is to expand the control range of the magnetic tape tension so that even if the tension of the magnetic tape exceeds the control range, the tension of the magnetic tape can be controlled.

To summarize this invention, when the tension of the magnetic tape is within a certain fixed value, voltage from the first power source is applied to the rotation drive means, and when the tension of the magnetic tape exceeds a certain fixed value, the first The second power supply is configured to apply a voltage of opposite polarity to the first power supply to the rotary drive means to reduce the drive torque.

Other objects and features of this invention will become clearer from the detailed description given below with reference to the drawings.

FIG. 3 is a circuit diagram of a magnetic tape winding device according to an embodiment of this invention.

In the configuration, the positive line of the power supply 12 is connected to the resistor 1
3 to the anode end of the light emitting diode 10, and its negative end is grounded. light emitting diode 1
The cathode end of 0 is grounded. Further, the positive end of the power supply 12 is grounded via a resistor 14 and a phototransistor 11. One end of the resistor 14 is connected to the base end of the transistor 15. transistor 1
The emitter end of the transistor 5 is connected to the positive line of the power supply 12 via the resistor 16, and the collector end is connected to the base end of the transistor 18. transistor 18
The emitter end of is grounded via the motor 2, and via a series circuit of a resistor 19 and a power supply 20 in parallel with the motor 2. Further, the negative terminal of the power supply 20 is connected to the base side of the transistor 18 via a resistor 21 for providing a stable voltage to the base of the transistor 18.

The operation of the magnetic tape winding device of this invention will be described below with reference to FIGS. 1 and 3.

When the motor 2 starts rotating and the take-up reel 5 starts winding the magnetic tape 4, the tension of the magnetic tape 4 is applied to the pole 61. With this, lever 6
begins to rotate clockwise against the elastic force of spring 9. At this time, the light shielding piece 62 moves to the left in the figure and gradually begins to shield the light from the light emitting diode 10. At this time, since the tension of the magnetic tape 4 is within the control range, the tension is controlled to be constant.

Further, the magnetic tape 4 is wound around the take-up reel 5, and the rotational friction torque of the motor 2 is, for example, 13g-
cm, the tension of the magnetic tape 49 exceeds 10 g. The light shielding piece 62 is connected to the light emitting diode 1.
Completely blocks 0 light. In other words, the tension of the magnetic tape 4 cannot be controlled. in this case,
Since the phototransistor 11 does not receive any light, the collector-emitter current decreases. Accordingly, the voltage at the base of transistor 15 increases, and the collector-emitter current of transistor 15 decreases. This causes transistor 18
The voltage at the base terminal decreases and enters the cut-off state. When transistor 18 is cut off, no current from power supply 12 flows to motor 2.
At this time, the motor 2 is connected to the power supply 1 through the resistor 19.
A negative current of opposite polarity to the current from 2 flows. Correspondingly, the torque of the motor 2 is reduced, so that the tension on the magnetic tape 4 is reduced. As a result, the light shielding piece 62 is returned to the right from the position where it blocks all light from the light emitting diode 10, so that the tension of the magnetic tape 4 can be controlled. In this way, even if the tension of the magnetic tape 4 exceeds 10 g, the tension of the magnetic tape 4 can be controlled.

Although this embodiment describes the case where a video tape recorder is used to wind a reel-to-reel magnetic tape, the present invention is not limited to this. Of course, the technical idea of this invention can also be applied to tape tension control when a magnetic tape is used.

As described above, according to this invention, when the tension of the magnetic tape is within a certain certain value, the voltage from the first power source is applied to the rotation driving means, and when the tension of the magnetic tape exceeds a certain certain value. At this time, the control range of the tension of the magnetic tape can be expanded by applying a voltage of opposite polarity to the first power source from the second power source to the rotary drive means and reducing the driving torque.
Therefore, the tension of the magnetic tape can be kept constant at all times, and accurate recording can be performed.

[Brief explanation of the drawing]

FIG. 1 provides the background to this invention and is a diagram showing a part of a conventional magnetic tape winding device. FIG. 2 is a circuit diagram of a conventional magnetic tape winding device. FIG. 3 is a circuit diagram of a magnetic tape winding device according to an embodiment of this invention. In the figure, 1 is a mounting plate, 2 is a motor, 3 is a rotating shaft, 4 is a magnetic tape, 5 is a take-up reel, 6 is a lever, 61 is a pole, 62 is a light shielding piece, 9 is a spring, 10 is a light emitting diode, 11 is a phototransistor, 12, 20 is a power supply, 13, 14, 1
6, 19, and 21 are resistors, and 15 and 18 are transistors.

Claims (1)

[Claims for Utility Model Registration] A winding means for winding a magnetic tape, a rotary drive means for rotationally driving the winding means, a mechanical deflection that contacts the magnetic tape and mechanically deflects according to the tension of the magnetic tape. a mechanism, a detection means for detecting a mechanical bias of the mechanical biasing mechanism, a first power supply that outputs a certain voltage, a second power supply that outputs a voltage of opposite polarity to the first power supply, and the magnetism. When the tension of the magnetic tape is within a certain constant value, a voltage from the first power source is selected and applied to the rotation driving means according to the output of the detection means, and the tension of the magnetic tape is within a certain constant value. A magnetic tape winding device comprising: control means for applying a voltage of opposite polarity from the second power source to the rotary drive means to reduce the drive torque when the value exceeds the output of the detection means. Device.